This step-mother won't let him burn in hell, and that's her promise to her step-son. She finds out some things about him that weren't acceptable to her and some were downright sinful. She says what she is about to do helped save his step-brother's soul. Now it's time for her to save his soul. That's her duty as her step-mother. Hence, she offers herself to her step-son so she can be his step-sonal cum-dump and lets him ejaculate in her as many times as he would like so none of his sperms go to waste.